1. Field of the Invention
The present invention relates to techniques for sealing cylindrical bodies to circumscribing conduits and, specifically, to an insert seal assembly for sealing a well tubing string within the bore of a surrounding well conduit.
2. Description of the Prior Art
Sealing devices of various kinds are used in well working operations, and in the production of a well. For example, in downhole cementing procedures, seal assemblies are used to control the placement of cement and the maintenance of pressure to accomplish cementing operations. Seal assemblies in the form of packers are known for isolating formations for treatment, or for isolating segments of liner or casing for squeeze cementing, for example. Packers are also used routinely for sealing production strings to liner or casing to define flow paths from producing formations to the surface.
In the case of production packers, the seal assemblies which are used to isolate the formations and define flow paths to the surface are set within a production casing or liner. The casing or liner is usually made up to include a sequence of tubular members threaded together. One of the tubular subs is provided with an internal recess, usually a circumferential groove, in proximity to a landing shoulder within the sub. The seal assembly is landed on the landing shoulder within the liner sub and has radially movable dogs which are actuated to latch the seal assembly into the internal recess provided in the pipe sub.
In prior seal assemblies of the above type, an outer sleeve was carried about a sliding inner mandrel. In certain of these tools, the latching dogs were driven radially outwardly into latching engagement with the recess provided in the surrounding liner. During production operations when pressure is on the tool, the latching dogs were subjected to loads which could damage the exterior surface of the sliding mandrel. The damaged mandrel could, in turn, damage that portion of the seal assembly used to seal between the mandrel and the surrounding conduit.
The present invention has as its object the provision of a seal assembly with an outer sleeve and inner sliding mandrel which includes an unique internal sliding sleeve that supports the setting dogs to prevent damage to the exterior surface of the sliding mandrel during production operations.